KVM paravirt: Move kvm_smp_prepare_boot_cpu() from kvmclock.c to kvm.c.

Async PF also needs to hook into smp_prepare_boot_cpu so move the hook
into generic code.

Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

arch/x86/include/asm/kvm_para.h

@@ -65,6 +65,7 @@ struct kvm_mmu_op_release_pt {
 #include <asm/processor.h>
 
 extern void kvmclock_init(void);
+extern int kvm_register_clock(char *txt);
 
 
 /* This instruction is vmcall.  On non-VT architectures, it will generate a